1. Technical Field
This invention relates in general to packet switches and, more particularly, to a method and apparatus for efficiently controlling flows between queues in a packet switch.
2. Description of the Related Art
Packet switches (also referred to as “routers”) are used throughout communications networks to route information. Typically, a packet switch has input and output ports, with respective input and output queues, to temporarily store data passing through the switch. In order to reduce the probability of overflow, flow control logic is generally required.
Present day flow control logic controls either the absolute quantity of data that can be sent from the input port to the output port or the rate at which data can be sent from input port to output port.
A complicating factor in flow control logic is the time delay in the delivery of the control packets, which regulate the flow. Delivery of flow control packets through the switch slows down the available data flow and, hence, it is preferable to use a few control packets as possible. On the other hand, using long times between data packets increases the chance that the information in the control packet may be out of date. Out of date control information may lead to changes in the flow between input and output queues which increase congestion.
Accordingly, a need has arisen for a packet switch with efficient flow control logic.